A distributed database, Blockchain is dispensed by all nodes in blockchain network. In easier terms to understand, this indicates that all nodes run on particular same software, holding a local copy of the entire database, and standardly talk to one and another to cultivate data and validate it.

How do I understand Immutability?

Immutable is defined as something that is unchanging over time or unable to be changed. In our terms, it tells that once data has been coded to a blockchain no human, considering a system, not even a system administrator, can alter it. This gives a hold of an audit. In simple terms as a provider of data you can factually show that your data has not been changed, and as a recipient of data, you can assure that the data has not been changed.

Immutability is relative. For instance, if I compose an email to a big list of acquaintances and send it, that data is to an extent immutable from my point of view. To alter it, I’d have to convince my acquaintances each to remove the email (or convince Gmail and the personalities running the mail servers of my acquaintances). From my point of view and with the control I possess, my email is immutable – I cannot possibly unsent it without several requests and risk of detection.

What is a private DataBase?

Private Database is a security feature that is constructed into a database server, as opposed to being a portion of an application that is ingressing the data. The user is only allowed to view the data they have been permitted to see. So no single troublemaker will be able to alter the Data and cause a ruckus. In prevailing systems and organisations, we try to impart divisions of responsibility, so that no single entity can do something bad without detection.

For instance, an administrator can ingress to change the blockchaindatabase, but the logs of the particular software may be stored on a different system which is owned and looked over by another entity. These organisational systems are put in place to make sure that an individual does not bring about any changes. We should entrust the organisational system of its works. However, there is no controlling entity that makes the data immutable, to begin with.

Blockchains

Blockchains are mandatory databases with some inbuilt pre-agreed technical and business logic criteria, kept in synchronization through peer-to-peer mechanisms and pre-agreed rules about what new data can be added. In terms of immutability, detection of intrusion is done with two key entities: hashes and blocks.

Hashes: A hash function is a mathematical function which converts data into a fingerprint of that particular data called a hash. It’s like an algorithm that takes the input data and converts it into an output of a fixed length, which denotes the fingerprint of that particular data. There are many varieties of hash functions. The common robust one is called SHA-256 (which denotes Secure Hash Algorithm – 256 bit)

Two important features of Hash are:

It’s very difficult to back-calculate the original data from the hash

If the input data is altered even to the least, the hash changes in a nondiagnostic way

Blocks: A notable idea in Bitcoin’s blockchain is that transactions are gathered into blocks before getting added to the blockchain database. Blocks hold the bitcoin transactions (payments) and also holds other data inclusive of the previous block’s hash. As each block considers the previous block’s hash as part of the data, a chain of blocks is formed. In a blockchain, instead of taking a reference to block numbers, blocks are referred by their hash and every block shows specifically about which block (hash) it is constructed on. Here is a simple way of understanding it.

Key Points:-

Each block’s hash is taken from the block's contents

Each block refers to the previous block’s hash

Data in a blockchain is stable internally.

Isolated Blockchain Data

Bitcoin’s blockchain consists of 400,000 blocks. If you remove a transaction from block 200,000 which is in the middle of the blockchain, trying to project that a payment has not happened, what will it result in??

1. The block’s hash fails

Initially, the regulator will re-calculate the block hashes based on the block data, and ensure that the block hashes produced are valid and equates with the contents of each block. If there is any alteration, it means that the transaction is altered.

2. The chain fails

The discrepancy in the hash leads to breakage of the chain. This is because each block holds the previous block’s hash. If block 200,000’s hash is altered, then the block 200,001 will have no reference it is based on. Block 200,001 will search for the old reference resulting in a broken blockchain chain which is a straight cut failure. You need to rebuild the whole chain to make it work again.

3. Chains are hard to rebuild

For public proof-of-work blockchains such as Bitcoin, a block is only considered authenticated if the block hash trails a strict pattern – the hash should be smaller than a target number, illustrated by “starting with a certain number of zeroes”. Recalculate the block’s hash alone is not enough, but it should be made sure that the recalculated hash is less than a particular number. You need to re-mine the blocks till you find a lesser valued hash.

Blockchains with Multiple Copies

If the hash on the last block on a particular copy is different to the from another participant, then the regulator can instantaneously spot that there is a breach in the blocks and the particular copy of the chain is different from the live blockchain. These properties of block chains have good and bad implications for the protection of saved data, and data privacy.

Applancer is an open platform for discussion on all things like Blockchain , Cryptocurrency and Ico news updates. As such, the opinions expressed in this article are the author's own and do not necessarily reflect the view of Applancer .